Art of making white lead



-($pecimens.)

G. D.. COLEMAN. ART OF MAKING WHITE LEAD.

No. 481,007. Patented Aug. 16, 1892.

J Tit 13 2 2 1/54 Jl METAL LEVEL.

ATTEST: 1 16.5. INVENTOR:

8 12, Geo. D.CoZeman, 5y

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N'rsn STATES GEORGE D. COLEMAN, OF CHICAGO, ILLINOIS.

ART OF MAKING WHITE LEAD.

SPECIFICATION forming part of Letters Patent No. 481,007, dated August16, 1892.

Application filed August 12, 1890. Renewed May 23, 1892. Serial No.434,105. (Specimena) To all whom it may concern:

Be it known that I, GEORGE D. COLEMAN, a citizen of the United States,residing at Chicago, 1n the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in the Art of CorrodingLead; and I do hereby declare the following to be a full, clear, andexact description of the same, such as will enable those skilled in theart to which the invention appertains to use and carry on the same.

The present invention relates to the treatment of metallic lead in adivided or comminuted state so as to corrode the same and produce atwill either of the following lead products or compounds, viz: leadsuboxide, lead protoxide, or lead hydrocarbonate, commonly called whitelead, or mixtures of either of the same.

The present invention has as its basis the recognition and applicationof the primary and fundamental fact that the chemical reactions in theinterior of the apparatus are greatly dependent upon and sensitive aswell as responsive to even comparatively moderate physical changes ofpressure and temperature. By the proper regulation and control of suchphysical agencies I am enabled in my present process to hasten or retardchemical action to such a degree that lead suboxide, lead protoxide, orlead hydrocarbonate can be pro duced at will as distinct and separatearticles of manufacture. A want of recognition and an absence of controland regulation of such physical agencies in what may be termed thetumbling process of producing white lead have heretofore rendered allsuch prior attempts to manufacture white lead unsuccessful, based asthey were upon the misconception that chemical forces alone neededattention and were to be depended upon alone to bring the growth anddevelopment of this tumbling process to a practical success.

My present improvement therefore embraces a process of treatingcomminuted metallic lead in which the temperature and pressure are undercomplete control and regulation so as to enable the production at willof either lead suboxide, lead protoxide, or lead In carrying out mypresent improved process or art of corroding lead I make use of a closedcorroding-vessel arranged to rotate and preferably constructed andarranged in the manner illustrated in the accompanying drawings, inwhich- Figure l is a general elevation, partly in section, of a form ofapparatus adapted for use in carrying out my present process; Figs. 2and 3, detail longitudinal or axial sections of the revolving cylinderand the connections thereto; Fig. 4, a detail elevation of theaxially-arranged pipes through which the water and gases pass to theinterior of the cylinder, and Fig. 5 a cross-section of the same at line00 00.

Similar numerals of reference indicate like parts in the several views.

In the construction shown in the aforesaid drawings the cylinder or cask1 for containing the comminuted lead, water, and gases is mounted inbearings on a suitable frame or base so as to rotate, motion beingcommunicated to the cylinder by any suitable means, preferably by tightand loose pulleys 2 and 3 upon a pinion-shaft that drives the spur-gear4, keyed or otherwise secured to the hub or axle of the cylinder 1, themetal-level and the water-level being indicated by dotted lines in saidfigure, the water-level being a little below the axis of the cylinderand above the inner downwardly-projecting end or neck of the siphon oroutlet-pipe 5.

The finely-divided metallic lead is introduced into the cylinder througha hand-hole in any suitable manner, but preferably in a substantiallycontinuous manner automatically, and enough. water isintroduced to fullycover the lead, preferably in bulk three or four times the amount oflead, the water-level being in any case below the axis of the cylinder.

ater is supplied to the cylinder 1 from an elevated closed tank 6 by avalved pipe 7, that connects with the axially-arranged pipe 8, arrangedin the cylinder, which is of same diameter and slotted longitudinally,as shown, so as to discharge water in a very uniform manner.

The supply of carbonic-acid gas and air is received under pressure fromany suitable source through the pipes 9 and 10, that join ICO togetherin a eommingling-pipe 11, that discharges into the interior of thecylinder through the longitndinally-extending perforated pipe 12,arranged concentrically within the slotted water-pipe 8, as clearlyindicated in Figs. 2, 3, 4:, and 5. The outlet from the cylinder isthrough the siphon or dischargepipe 5, passing through the hollow axisof the cylinder and discharging into the tub or filter 13.Packing-glands 14, 15, and 16 are provided on the axial parts tomaintain tight joints between the pipes 12, 8, and 5 and the hollow axisof the cylinder, as clearly illus trated in Figs. 2 and 3.

In the construction illustrated, l7 represents a pressure-gage connectedto the inletpipe for the gases to indicate the pressure of the same, and18 a similar gage for indicating the pressure of water in the tank 6.

19 is a suitably-constructed pump having its supply connected to thefilter of tub 13 and its discharge connected to the elevated closed tank6 by a pipe 20, the purpose being to cause a continuous circulation ofthe water from the tank 6 through the corroding-cylinderl to the filter13, and from thence by means of the pump 19 returned back to the tank 6.

The apparatus herein described is substantially the same as that setforth and claimed in my application for Letters Patent for improvementin apparatus for corroding lead filed August 17, 1891, Serial No.402,921, and I make no claim in the present application to features ofconstruction embodied in the aforesaid application, Serial No. $02,921.

In carrying my improved process into effect the following generaldirections may be ob served: Charge the corroding-cylinder (usually of asize four feet in diameter and five feet long) with a proper quantity ofgranulated lead and sufficient water to reach an indicated water-levelbelow the axis of the cylinder and air, either alone or combined withcarbonic-acid gasinabout equal vol um es, to fill the space above thewater. Then impart rotary movement to the cylinder, usually forty tosixty-five revolutions per minute, un' til the resultant product is of abluish tint. Preserveacontinuonsinfiowingandontflowing stream of waterthrough the cylinder in order to attain the following results: Thecontrol and regulation of the temperature in the cylin der by increasingor decreasing the volume, temperature, or flow of the water and thewashing out and removal of the products of corrosion from the cylinder,so as to keep the lead bright and clean and in the best possiblecondition for oxidation, attrition, and carbonation in a contin nousmanner and at the same time afford a continuous sample of the productfor inspection at the point of discharge from the water-eduction pipe,the gas-supply under pressure being maintained intact by any usualmeans.

From practical experiment I find the following degrees of temperatureand pressure best adapted to the rapid formation of the differentdesired products of the present corroding process, to wit: leadsuboxide, lead protoxide, and lead hydrocarbonate or a mixture of thesame.

Formula 1.For the production of lead suboxide, a temperature of 150 to210 Fahrenheit and under the ordinary atmospheric pressure.

Formula 2.For the production of lead bydrocarbonate or white lead, atemperature of to 150 Fahrenheit and a pressure of thirty pounds.

FormaZa 3.For the production of lead protoxide, a temperature of 75 to150 Fahrenheit and a pressure of fifteen pounds.

Formula 4.For the production of a mixture of lead suboxide, leadprotoxide, and lead hydrocarbonate, a temperature of 32 to 75 Fahrenheitand a pressure of fifteen pounds.

If the purpose is to produce lead suboxide, formula 1 will be followeduntil the charge is oxidized and converted into substantially pure leadsuboxide, as indicated by its blueblack color. In following this formulathe presence of air alone is required, and the supply of carbonic-acidgas will in consequence be cut off.

\Vhite lead can be made directly by following formula 2 and rotating thecorrodingcylinder, according to the general instructions therefor, untilits contents are oxidized and carbonated and have a blue tint andconsist of white lead colored by a little lead suboxide, which can besubsequently treated in any suitable manner with air and carbonic acidto be converted to a uniform standard of color, the.

Lead protoxide can be made by following formula 3 and rotating thecylinder according to the general directions or until its contents areoxidized and consist of substantiallypure lead protoxide, as indicatedby the yellow color and the proper tests.

hite lead can also be made by following formula 4 and rotating thecylinder and otherwise proceeding as in formula 2.

Formula 1 is the best for making lead suboxide, the high temperaturecausing rapid oxidation, and at the same time a strictly pure leadsuboxide is formed under new physical and chemical conditions that giveit an unequaled facility of oxidation and carbonation.

The effect and importance of pressure in raising the decomposingtemperature of white lead is shown in formulas 1 and 2, where it israised from 75 Fahrenheit in formula 1 to 150 Fahrenheit in formula 2 byincreasing the pressure from fifteen pounds in formula 1 to thirtypounds in formula 2. By such means it becomes practicable to use thosetemperatures and pressures that are the most simple and effective inoperation and at the same time the most rapid and desirable in theproducts and other results obtained therefrom. In fact, it thus becomesa possible and simple matter to calculate in advance a pressure andtemperature combination or formula suited to the use of any particularpressure or temperature that may be desired for any special use orpurpose. In view, therefore, of the great number of such rules orcombinations that would have a practical and important application forthe purposes herein specified, I do not confine my present invention toany one precise or particular formula heretofore given, and may modifyand change the same as particular circumstances and the judgment of theoperator may suggest without departing from the spirit of my presentinvention.

Having thus fully described my said invention, what I claim as new, anddesire to secure by Letters Patent, is

1. The herein-described improvement in the art of corroding lead in thepresence of water and a suitable corroding-gas, the same consisting inpreserving the surface of the lead particles in a clean condition bestadapted for corrosive action by a flow of water that acts to remove thecorroded lead as fast as formed, substantially as herein described.

2. The herein-described improvement in the art of corroding lead in thepresence of water and a suitable corroding-gas, the same consisting inconducting the corroding process under definite and controllable degreesof pressure and temperature and at the same time preserving the surfacesof the lead particles in a clean condition best adapted for corrosiveaction by a flow of Water that acts to remove the corroded lead as fastas formed as well as to carry off the surplus heat generated by thephysical and chemical reactions in the process, substantially as hereindescribed.

In witness whereof I hereunto subscribe my name this 9th day of August,A. D. 1890.

GEORGE D. COLEMAN. Witnesses:

GEORGE P. BARTON, ELLA EDLER.

